The Carlos Tevez saga took a dramatic twist in the high court yesterday when West Ham United's lawyers challenged the authenticity of a document presented by Media Sports Investment and Just Sports Inc. The document, filed at a depositions hearing, was a contract drawn up on December 1 at the insistence of the West Ham chairman, Eggert Magnusson. It stated that on July 1 Tevez would be released from the club and stipulated that, if he remained at Upton Park, MSI-JSI would have to make payments that would effectively cover his wages.

MSI-JSI consider the document central to their breach-of-contract case against the Hammers, in which they demand that Tevez be freed from his obligations with West Ham and permitted to move to Manchester United. The hearing will take place over three days from August 22.

West Ham say the document was rescinded and its terms were never executed because it was not countersigned by Tevez. But the copy of the document filed at yesterday's hearing was furnished with dates and signatures, prompting West Ham's challenge over its authenticity.

MSI-JSI interpret this as a delaying tactic but it is believed the club's lawyers are preparing to call a graphologist and forensic experts at the hearing. MSI-JSI's counsel will respond by calling Tevez, Magnusson and the West Ham chief executive, Scott Duxbury, to give evidence under oath.

The debate about the authenticity of the document might most simply be settled by the Premier League's chief executive, Richard Scudamore, whose organisation received a copy before a disciplinary commission hearing in April. Scudamore is also set to be subpoenaed by the offshore companies, which are fronted by Kia Joorabchian.

West Ham hope a negotiated settlement can be achieved before August 22. However, MSI-JSI have not received the proposed terms of any compromise agreement because these must first be approved by the Premier League.

That may prove difficult because the league is holding the club to their undertakings in May. This was when they informed the league they had torn up all third-party contracts relating to Tevez and MSI-JSI.